Understanding the factors that constrain or promote symbiotic microbial communities gives a clearer picture of the niches that can be occupied by a host organism. Many insects harbor symbiotic microbes that can alter various aspects of insect behavior and biology including digestion, sex determination, and pathogen defense. Habitat diversity has a major influence on insect and microbial diversity within an environment. In the current study, we assessed how habitat biodiversity affects the bacterial species richness within the gastrointestinal tract of insects. We measured species abundance of plants and insects present in three replicated habitats (prairie, pasture, and maize fields) that inherently represent a continuum of biological diversities. Gut bacterial symbiont diversity of the crickets Gryllus pennsylvanicus Burmeister and Allonemobius sp. (Orthoptera: Gryllidae) were described using terminal restriction fragment length polymorphism analysis of rRNA genes. The resulting data show that gut bacterial diversity of both cricket species is positively correlated with biodiversity according to habitat type. This demonstrates that microbial diversity within insect gastrointestinal tracts, and possibly their functions within these insects, is tied to the biodiversity within the habitats where insects live. These results have important implications as to how reductions in habitat biodiversity may affect the ecological functions and services that the remaining species can perform.